In a general game device, when providing a detection target region group in which detection target regions are adjacently disposed in parallel and detecting the detection target region through which a game medium has passed, a pair of optical sensors is disposed corresponding to each detection target region, and the game medium is allowed to pass between the pair of optical sensors to detect the game medium.
The applicant of the invention has proposed disposing light-emitting/receiving elements of an optical sensor in the detection target region so that the optical axis passes diagonally from one side to the other side of the passage direction of the game medium to reliably detect the rotating disk-shaped game medium (see Patent Document 1).    Patent Document 1: JP-A-2001-224835